1. Technical Field
The present invention relates to a liquid ejecting head ejecting a liquid from nozzle openings and a liquid ejecting apparatus, and, specifically, to an ink jet type recording head ejecting ink as the liquid and an ink jet type recording apparatus.
2. Related Art
As an ink jet type recording head that is a representative example of a liquid ejecting head ejecting liquid droplets, for example, there is an ink jet type recording head that includes nozzle openings and a flow path of a pressure generation chamber communicating with the nozzle openings and the like, in which ink droplets are ejected from the nozzle openings by generating a pressure change in ink inside the pressure generation chamber caused by a pressure generation unit.
In such an ink jet type recording head, components contained in the ink evaporate from the nozzle openings so that the ink is thickened and variation occurs in ejection characteristics of the ink droplets with elapse of time, and then ejection quality of the liquid cannot be maintained to be constant. Furthermore, if the components contained in the ink settle and a difference occurs between components of the ink droplets when continuously ejecting the ink and components of the ink droplets when ejecting the ink at time intervals, variation also occurs in the ejection quality of the liquid.
Thus, an ink jet type recording head is suggested in which ink is supplied to a manifold that is a common liquid chamber communicating commonly with a plurality of pressure generation chambers and the ink is recovered from the manifold, and the ink is circulated by repeating the supply and recovery, thereby thickening of the ink and settling of the components contained in the ink being suppressed (for example, see JP-A-2009-247938 and Japanese Patent No. 3161095).
However, even if the ink inside the manifold is circulated, a temperature difference (temperature gradient) occurs between a temperature of a center of ink flow inside the manifold and a temperature of the ink inside the pressure generation chamber to which the ink is supplied from the manifold, and even if the ink having a desired temperature is circulated inside the manifold, the temperature of the ink inside the pressure generation chamber is lower than that of the ink inside the manifold so that there are problems that the ink cannot be ejected at an optimum temperature and optimum ejection characteristics cannot be obtained.
Furthermore, if a volume of the manifold is reduced, a temperature gradient of the ink between a side of a liquid ejecting surface and a side opposite to the liquid ejecting surface inside the manifold or a temperature gradient of the ink in an arrangement direction of the pressure generation chambers can be reduced, but there are problems that pressure loss is increased, a change in a pressure of the pressure generation unit cannot be absorbed on the side of the manifold, crosstalk occurs, and the like.
Thus, a configuration is disclosed in which a temperature gradient of ink inside a manifold is suppressed by providing a protrusion section within the manifold without remarkably reducing a volume of the manifold (for example, see JP-A-2013-230659).
However, in JP-A-2013-230659, a center of ink flow flowing inside the manifold is moved and the temperature gradient of the ink inside the manifold can be suppressed by providing a protrusion section inside the manifold, but there are problems that air bubbles stagnate in a corner portion and the like formed by the protrusion section and a wall surface of the manifold and the air bubbles enter the pressure generation chamber and the like at an unexpected timing, and there is a concern that defects such as ink ejection failure may occur.
Furthermore, when the air bubbles stagnating inside the manifold grow, there are problems that the air bubbles becomes a buffer to a region facing the air bubbles in the pressure generation chamber communicating with the manifold and affect a pressure fluctuation in the pressure generation chamber, a variation in the pressure fluctuation occurs between the pressure generation chamber communicating with the manifold in the region facing the air bubbles and the pressure generation chamber communicating with the manifold in a region not facing the air bubbles, and there is a concern that a variation occurs in ejection characteristics of ink droplets.
Moreover, such problems also similarly exist in a liquid ejecting head ejecting a liquid other than ink in addition to the ink jet type recording head.